• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.40-42
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• 2009

The economic growth and highly industrialized society have increased the demand for electricity power. As a result, concerns were focused on the energy resource scarcity and global warming. That is why the photovoltaic generation system to address these concerns has been in the spotlight recently. In this thesis, a utility interactive photovoltaic generation system was operated experimentally for the purpose of promoting the spread of the photovoltaic generation system in the future. Also, the effect of the type of array structure has on the performance of the photovoltaic generation system was evaluated quantitatively and by analyzing the comprehensive operating characteristics, the following results were obtained. In the demo system operated for a year, the average irradiation was measured to be 455,076 $[W/m^2]$ and the maximum irradiation to be 626,622 $[W/m^2]$ in May, up 171,546 $[W/m^2]$ or 38[%] compared with the average irradiation. The minimum irradiation was observed to be 294,022$[W/m^2]$ in December, down 161,054 $[W/m^2]$ or 35[%] compared with the average irradiation. The generation power in situation where there is plenty of irradiation was more than the average one, and the generation power in the fixed system amounted to 32[%], the single-axis tracker to 37[%], and the dual-axis tracker to 39[%]. The generation power in situation where there is little irradiation was less than the average one, and the generation power in the dual-axis tracker amounted to 41[%], the single-axis tracker to 40[%], and the fixed system to 36[%].

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.5
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• pp.280-286
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• 2006

The paper proposes a new protection algorithm for reliable operation of grid-interfaced PV system, which can flexibly interact with conventional protective schemes of power utility grid not only to prevent damages to utility or public persons and utility apparatus caused by malfunction or failure in distribution network protection system, but also to protect a PV system itself from faults or abnormal conditions of the network. The proposed algorithm is based on reclosing characteristics of the distribution system. As a network fault occurs, the new scheme determines whether it is momentary or permanent and responds in a pre-programmed way to the fault. For permanent outage, the proposed algorithm shuts down inverter's operations but monitoring system voltage and frequency at the point of common coupling with grid. When it comes to the momentary outage, Inverter starts stand-by operation mode so that it can be automatically connected to the grid without start-up procedures as soon as the system voltage and frequency returns into the normal operation range. In order to investigate' and evaluate the PV system operation, simulation study based on PSCAD/EMTDC has been carried out to verify the performance of the proposed protection scheme.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.133-136
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• 2004

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1253-1255
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• 2003

Since the residential load is an AC load and the output of solar cell is a DC Power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation. it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.4
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• pp.16-22
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• 2000

This paper describes Transformer-less type utility interactive system that is combined with buck/boost chopper applying partial resonant method, which remove Transformer, and high efficient PWM inverter. Therefore, it is possible to make it lightweight, to cut down the cost, and to improve its reliability. What the merits of this system are that we can transmit arbitrary power arbitrary power to load and utility regardless of generating voltage magnitude of solar cell and we can always obtain high factor controlling by equal phase signal with utility.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.277-280
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• 2002

With significant development of power electronics technology, the proliferation of nonlinear loads such as static power converters has deteriorated power quality in power transmission and distribution systems. Notably, voltage harmonics resulting from current harmonics produced by the nonlinear loads have become a serious problem in many countries. There are already a lot of PV power generation systems installed in building systems whose harmonics are the worst object for distribution systems as a utility interactive system and also it tends to spread out continuously. In this paper, the authors propose a multy-function inverter control strategy which puts a shunt active filter function to the power inverter of the PV power generation system established on a building system. The effectiveness of the proposed system is demonstrated through the simulation of hypothetical power system using PSCAD/EMTDC.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.724-729
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• 1998

In general, a single-phase current-fed PWM inverter using IGBTs has some unique advantages for small scale distributed utility-interactive power supply system as compared with voltage-fed PWM inverter. In particular, this is more suitable and acceptable for a non-isolated type utility-interactive power conditioner, which is going to be widely used for residential solar photovoltaic (PV) power generation system in Japan. However, this current-fed PWM inverter has a significant disadvantage. The output current of this inverter includes large harmonic contents when the inductance of smoothing reactor in its DC side is not large enough to eliminate its current ripple components of this inverter. In order to overcome this problem, a new conceptual pulse area modulation scheme for this inverter is introduced in difference with conventional PWM strategy. This paper presents a new effective control implementation of this PV power conditioner which is able to reduce the harmonic component in the output current produced by the single-phase current-fed PWM inverter even when the ripple current in the smoothing DC reactor is relatively large. The operating principle of the proposed control strategy introdued for this inverter system is described, and its simulation results are evaluated and discussed herein.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.420-428
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• 2018

In this paper, represented uninterruptible power supply (UPS) equipment maintaining constant output voltage, the proposes a photovoltaic system constructed with a step up boosting chopper and single phase pulse width modulation (PWM) voltage source inverter. as power source disconnection, voltage variation and output current variation with load variation. This system is driven by being synchronized voltage fed inverter and AC source, and in the steady state of power source charge battery connected to DC side with solar cell using a Photovoltaic that it was so called constant voltage charge. It can be results of saving electric power, and through a normal operation of energy storage system (ESS), the system operated the LED a calling on signal changes at the airport in an efficient manner. In addition, better output waveform was generated because of PWM method, and it was proved to test by experiment maintained constant output voltage regardless of AC source disconnection, load variation, and voltage variation of AC power source.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.157-168
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• 2009

In this paper, a photovoltaic system is designed with a step up chopper and single phase PWM(Pulse Width Modulation) voltage source inverter. Where proposed Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature because solar cell has typical voltage and current dropping character. The single phase PWM voltage source the inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power. from 10 to 20[%]. The single phase PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In order to enhance the efficiency of photovoltaic cells, photovoltaic positioning system using sensor and microprocessor was design so that the fixed type of photovoltaic cells and photovoltaic positioning system were compared. In result, photovoltaic positioning system can improved 5% than fixed type of photovoltaic cells. In addition, I connected extra power to the system through operating the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and the phase of single-phase inverter of PWM voltage type can be synchronized. And, It controlled in order to provide stable pier to the load and the system through maintaining high lurer factor and low output power of harmonics.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.257-260
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• 2005

A very complicated real system can be simulated using hardware-in-the-loop (HIL) system in a virtual environment. Therefore, HIL system can speed up research and development process with a little effort. Also, current DSP for utility interactive photovoltaic generation system adopts floating point process type, which is easy to use for number crunching. However, fixed point process DSP, TMS320F2812, has high control speed and is rather inexpensive. This paper presents more efficient method for MPPT control using TMS320F2812 along with HIL system.